Networked lighting systems consist of luminaires, light sensors, and motion sensors, interconnected by means of a communication medium. The communication medium may be based e.g. on wires, RF technology or coded light. The interconnection between the devices enables a controlled lighting system, in which the information sensed by the sensors may control the luminaires and in particular determine the intensity settings of these luminaires.
Well known functionalities offered by these networked lighting systems are presence adaptation wherein luminaires are switched on only when people are present, and daylight adaptation wherein luminaires are dimmed when daylight enters a detection area. Illumination may thereby not need to be switched to full power to provide a user with a desired illumination level.
It is known to consider a network that includes M luminaires and N light sensors in a method for lighting control allowing for daylight adaptation in a networked lighting system. An N×M transfer matrix D is used to control the system. The entry Dsl of the transfer matrix expresses the impact of luminaire l on sensor s, in that a light intensity Il of luminaire l results in a sensed intensity Dsl Il at sensor s.
The matrix D may be learned in an automatic way by successively switching on and off the luminaires in the system and measuring the impact on the sensors. This knowledge of D may for instance be used for daylight adaptation of the lighting system.
In such networked lighting systems, occasionally a luminaire or sensor will fail. Such failure reduces the performance of the lighting system. Provided that a failed device is identified, its failure may be compensated for by another device. Consequently, there is a need for a method of identifying such failed luminaire or sensor. Further, there is a need for a method able to identify that both a luminaire and a sensor have failed simultaneously.